Thesis (Ph. D., Microbiology, Molecular Biology and Biochemistry)--University of Idaho, September 2006. / Major professor: Gregory Bohach. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.

Thesis (Ph.D. ) - James Cook University, 2006. / Typescript (photocopy) Bibliography: leaves 262-302.

Thesis (Ph. D.)--Washington State University, May 2009. / Title from PDF title page (viewed on Apr. 20, 2010). "School of Economic Sciences." Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 73-81). Also available on the World Wide Web.

Thesis (M.S.)--University of Delaware, 2008. / Adviser: Kalmia E. Kniel. Includes bibliographical references.

Thesis--PlanA (M.S.)--University of Wisconsin--Stout, 1999. / Includes bibliographical references.

Foodborne illnesses following the ingestion of contaminated food are a major public health problem worldwide. They include a broad group of illnesses ranging from mild to chronic or life-threatening; caused by either toxins released from the disease-causing microbes, or by the microbes themselves. Antimicrobial susceptibility data shows an alarming increase in the frequency of antimicrobial resistance of foodborne pathogens, a situation which is worrisome as it decreases the effectiveness of drugs employed to reduce the morbidity and mortality associated with serious and life-threatening infections and thus, compromising human health. This study was therefore designed to assess the occurrence and characterization of bacterial foodborne pathogens in various foods sold in Alice, Eastern Cape Province of South Africa in an effort to throw more light on the inherent risk associated with such foods. The study was conducted during the period of 2011 - 2013. Two university restaurants and eight ready-to-eat food vending sites in Alice Town were selected based on their prominence to the students, workers and rest of the community. Microbiological analysis was conducted on 252 samples which included vegetables, potatoes, rice, pies, beef and chicken stew. The isolates were identified using biochemical tests and confirmation of the two most prevalent organisms (Listeria ivanovii and Enterobacter cloacae) was done using PCR techniques. The antimicrobial susceptibility profile of Listeria ivanovii and Enterobacter cloacae strains were identified using the disc diffusion technique; minimum inhibitory concentration was determined by the broth dilution method and M.I.C. Evaluator test strips. The microtiter plate adherence assay was employed to ascertain the ability of these isolates to adhere to a surface whereas the role of cell surface properties in biofilm formation was assessed using the coaggregation and autoaggregation assays. The architecture of the formed biofilms was examined under the scanning electron microscope. The virulence and resistant genes were also detected and characterised by sequencing the PCR products. Bacterial growth was present in all the food types tested; organisms isolated included: Listeria spp. (22%), Enterobacter spp. (18%), Aeromonas hydrophila (12%), Klebsiella oxytoca (8%), Proteus mirabilis (6.3%), Staphylococcus aureus (3.2%) and Pseudomonas luteola (2.4%). PCR confirmed 30 (97%) isolates as E. cloacae complex while 44% (22/50) tested positive for L. ivanovii. All the strains of E. cloacae (100%) and 96% of L. ivanovii isolates (based on phenotypic identification) were resistant to at least four or more of the antibiotics. In this study, bla-TEM was also detected from 48 (96%) of L. ivanovii and 30 (100%) of E. cloacae strains; further analysis of the bla-TEM demonstrated the occurrence of bla-TEM-1. Of the 56 bla-TEM-1 positive isolates sequenced, 7% (4/56) had mutation of either insertion or substitution of a nucleotide. Two virulence genes (ucaA and hlyA) were detected in E. cloacae isolates and none in L. ivanovii using PCR. Sequence analysis of the hsp60 gene reported the presence of two sub-species for E. cloacae; E. cloacae cluster III (75%) and E. cloacae cluster IV (25%); while analysis of the iap60 gene demonstrated that 55.8% (19/34) were L. ivanovii, 44% (15/34) L. seeligeri and 14.7% (5/34) L. welshemeri. A total of 90% L. ivanovii and 88% E. cloacae strains demonstrated the ability to form biofilms; the coaggregation index ranged from 12 to 77% while the autoaggregation index varied from 11 to 55% for L. ivanovii and 27% to 98% for E. cloacae. The findings of this study indicate that most of the ready-to-eat food samples examined did not meet bacteriological quality standards, thus posing potential risks to consumers. This should draw the attention of the relevant authorities to certify that hygienic standards are improved to curtain foodborne infections. Furthermore, the presence of multi-resistant strains is of major concern as these foods could serve as important vehicles transmitting multi-resistant bacteria and genes to humans. In addition the ability of these pathogens to form biofilms may lead to adherence of these organisms to kitchen utensils and other environments leading to cross-contamination of food processed in these areas and increase resistance of organisms to antimicrobial agents.

The 16S/23S ribosomal RNA (rRNA) intergenic space (IGS) regions from pathogenic and non-pathogenic species (spp.) of Listeria were characterized by the polymerase chain reaction (PCR) and DNA sequencing. DNA sequencing data for the small rRNA IGS region showed that this IGS was approximately 244 bp in length and was highly homologous (95 to 99 %) in five of the six Listeria spp examined; ie., L. monocytogenes, L. innocua, L. seeligeri, L. welshimeri, and L. ivanovii. A lower degree of homology (91 to 94 %) was detected in the large rRNA IGS region (ca. 494 bp) of these species. The DNA sequence data was used to develop two sets of oligonucleotide primers for PCR-based detection of the members of the genus Listeria. The first set of primers were Listeria genus-specific and, the second set of primers were L. monocytogenes-specific. / xv, 131 leaves ; 29 cm.

Thesis (M.P.H.)--University of Nevada, Reno, 2006. / "December, 2006." Includes bibliographical references (leaves 90-117). Online version available on the World Wide Web. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2006]. 1 microfilm reel ; 35 mm.

Thesis (M.S.)--University of Delaware, 2008. / Principal faculty advisor: Kalmia Kniel, Dept. of Animal & Food Sciences. Includes bibliographical references.